Flame Retardant Polyacrylonitrile Research Articles

Preparation of durable flame retardant PAN fabrics based on amidoximation and phosphorylation

Abstract This paper aims to develop a method to impart polyacrylonitrile (PAN) fabric durable flame retadancy. PAN fabric was modified with hydroxylamine hydrochloride (HA) to prepare amidoxime PAN fabric (A-PAN) followed by phosphorylation with phosphoric acid (PA) to obtain flame retardant PAN fabric (P-A-PAN). Thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), microscale combustion calorimetry (MCC) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) were used to analyze the thermal degradation process and flame retardant mechanisms. The structure of the fabrics was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). The surface morphology of fabrics was observed by scanning electron microscope (SEM). Moreover, the flame retardancy of fabrics before and after washing was evaluated by Limiting oxygen index (LOI) and horizontal burning test. The results showed that the P-A-PAN possessed an excellent thermal stability with the highest LOI value of 34.1% and the highest char residue of 55.67% at 800 °C. Most importantly, the P-A-PAN possessed a wonderful flame retardant durability with a little decrease of LOI after 20 washing cycles. When they were ignited, the P-A-PAN fabrics before and after washing were both nonflammable due to the char residue formation of modified fabric.

Flame retardant polyacrylonitrile fabrics prepared by organic-inorganic hybrid silica coating via sol-gel technique

Abstract The aim of this paper was to explore a novel technique to impart polyacrylonitrile (PAN) fabric flame retardancy. The fire retardant sol was firstly prepared by adding phytic acid and urea as phosphorus-nitrogen synergistic agent to tetraethoxysilane (TEOS). The resulting sol was then coated on PAN fabric and gelated to produce fire retardant PAN fabric. The structure, components, thermal properties and combustion performance of the resultant fabrics were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG), differential scanning calorimetry (DSC) analysis, limited oxygen index (LOI) test, and microscale combustion calorimeter (MCC). The results showed that the coated PAN fabrics possessed an excellent thermal stability and flame retardancy. Compared with the control sample, the fabric coated with phosphorus-doped silica coating (Si-P) was self-extinguishing when the fire source was removed. Furthermore, the fabric coated with phosphorus and nitrogen-doped silica coating (Si-P-N) was incombustible with the highest LOI value of 42.1%, displaying excellent fire retardancy.

UV-induced surface grafting polymerization for preparing phosphorus-containing flame retardant polyacrylonitrile fabric

In order to improve the flame retardancy of polyacrylonitrile (PAN) fiber fabric, hydroxyethyl methacrylate (HEMA) was first grafted onto the surface of PAN fiber fabric (PAN-g-HEMA) using ultroviolet (UV)-induced photo graft polymerization technology. Then, the PAN-g-HEMA fabric was reacted with phosphoric acid catalyzed by urea, to successfully obtain the flame retardant PAN fiber fabric (FR-PAN-g-HEMA). The optimum process of grafting was obtained. The structure of the fabrics was characterized with FTIR, XRD, XPS and SEM. The thermal analysis indicates that FR-PAN-g-HEMA fabric has good fire retardant properties with an LOI value of 32%.

Phosphorus-doped organic–inorganic hybrid silicon coating for improving fire retardancy of polyacrylonitrile fabric

In this study, in order to increase the flame retardancy of polyacrylonitrile fiber fabric, an organic–inorganic hybrid silane coating doped with polyphosphoric acid was prepared using tetraethoxysilane as the precursor by sol–gel technique. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope confirm the successful silicon and phosphorus-doped silicon coating on polyacrylonitrile fabric. Obviously, the char residue values at 800 °C of the silica-coated and phosphorus-doped silica coated polyacrylonitrile fabric samples were observed to increase 17.93 and 25.92%, respectively than that of the control sample. The peak and total heat releases of the phosphorus-doped silica coated polyacrylonitrile fabric significantly reduced to only 44.9 and 42.1% of that of polyacrylonitrile fabric, respectively. Besides, both the peak values of smoke production rate and total smoke production are remarkably reduced. The results show that the coated layer can effectively improve the thermal stability, and strengthen the ability to form a thermally stable and condensed barrier for heat and mass transfer. Furthermore, the phosphorus-doped silica-coated polyacrylonitrile fabric provided a novel and efficient method to prepare flame retardant polyacrylonitrile fabric with attractive features. In this article, an efficient and facile method was successfully demonstrated to prepare novel fire retardant PAN fabric. The organic–inorganic hybrid silane coating doped with polyphosphoric acid (PPA) can effectively retard the thermal degradation of PAN fabric, enhane the char-forming ability and can produce a stable and compact shielding layer. The phosphorus-doped silica-coated PAN fabric has lower values of pHRR, THR, pSPR, TSP, aMLR and FIGRA, compared to the control PAN fabric.

Preparation, flame retardancy and thermal degradation behaviors of polyacrylonitrile fibers modified with diethylenetriamine and zinc ions

A kind of flame-retardant polyacrylonitrile fiber was prepared successfully by the modification with diethylenetriamine and zinc ions (Zn2+). The chemical, aggregation and morphological structures of the aminated fibers were studied by Fourier transform infrared (FTIR) spectra, X-ray diffraction and scanning electron microscope (SEM). Meanwhile, mechanical and adsorption properties were investigated by a tensile tester and atomic absorption spectrometry. The flame retardancy of the modified fibers was significantly improved after modification. And the thermal degradation behaviors and flame retardancy mechanisms were studied in detail. The microscale combustion calorimeter and TG-FTIR results showed that the modified fibers decomposed less combustible gases and more non-combustible gases comparing the original fibers. And thermogravimetric analysis and SEM tests revealed that Zn2+ would stabilize the main chains and promote formation of compact char layers. And differential scanning calorimetry tests indicated that Zn2+ would inhibit the cyclization exothermic process. Results showed that the combination of gas phase and condensed phase mechanisms optimized the flame retardancy performance.

Structure and Properties of Hydrolyzed Cyclization-Crosslinking Flame-Retardant Polyacrylonitrile Fiber

As flame-retardant Polyacrylonitrile (PAN) fibers was one of the most important differential fibers, it was of great importance to make research on the modification of flame-retardant PAN fibers to improve its characteristics. In this present study, the flame-retardant PAN fiber with good moisture absorption and mechanical properties has been prepared treated by blending solution of sodium hydroxide and hydrazine hydrate. FTIR spectra presented that new amide and cyclization-crosslinking pyridine group band peaks appeared. X-ray diffraction showed that the crystal structure of PAN fibers has been converted from quasi-crystalline structure into partially crystallized structure after modification treatment. SEM micrographs indicated that the original longitudinal surface microgroove has changed to layered structure by surficial etchant.

Study on the Preparation of Flame-Retardant Polyacrylonitrile Fiber by Surface Modification

In this article, a new process was used to make flame resistant polyacrylonitrile (PAN) fibers by surface modification. The effects of the treating conditions during the copper ion treatment, aqueous mixture of hydrazine hydrate treatment and high temperature treatment on the mechanical properties and flammability of the resultant flame resistant fibers were studied. The results showed that the optimum reactiong conditions were: the addition of hydrazine hydrate 20mL, drying time 3min, heating temperature 160°C and heating time 180min.Under these conditions, the flame-retardant PAN fiber with good mechanical properties could be obtained.